Hormones of the hypothalamic pituitary axis (HP) exert direct behavioral effects, either by activation of specific receptors in brain or by modulation of central neurotransmitter systems. The synthesis and release of HP hormones is partially under the control of the monoaminergic neurotransmitters and is influenced by psychoative agents. Current studies concentrate on comprehensive tests of HP function and on the measurement and administration of specific behaviorally active peptides or peptide analogs. Major findings this year are: cerebrospinal fluid (CSF) vasopressin (VP) is significantly lower in drug-free depressed patients compared with controls. Desamino-8-D arginine vasopressin (DDAVP), a VP analog, enhances cognition in normals as well as in patients with affective illness. Patients with anorexia nervosa show a state independent increase in the CSF/plasma VP ratio and grossly disturbed osmoregulation of VP secretion. I.V. methadone infusion causes sustained suppression of plasma cortisol in depressed patients. The growth hormone and prolactin responses to I.V. arginine infusion are significantly greater in unipolar compared with bipolar depressed patients or controls.